Eric and Ryan Jensen, ages 37 and 33, of the now-bankrupt Jensen Farms were arrested Thursday and each charged with six misdemeanor counts of introducing adulterated food into interstate commerce.

The men appeared Thursday afternoon in U.S. District Court in Denver and were released on a $100,000 unsecured bond. The Jensens each could face up to six years in prison and up to $1.5 million in fines if they are convicted of all six counts, prosecutors said.

Their trial is scheduled for Dec. 2.

The cantaloupe growers' farm is considered the source of a national listeria outbreak that killed at least 33 and sickened another 147 people in 2011, one of the country's most deadly outbreaks of food-borne illness, according to government investigators.

The lawyer who represents 46 families in several civil lawsuits against the farmers issued a statement on his website Wednesday saying he was pleased the U.S. Attorney's Office has recognized "that some form of criminal sanctions were appropriate against Jensen Farms." Lawyer Bill Marler of Seattle first urged the U.S. Attorney's Office to consider criminal charges last year.

Criminal charges in food poisoning cases are rare, Marler said Thursday. Only four other people have faced such charges in the past decade.

He noted that felony charges would have required prosecutors to show the contamination was intentional.

"The real significance of the case against the Jensens is they are being charged with misdemeanors, which do not require intent, just the fact that they shipped contaminated food using interstate commerce," he said.

After Thursday's hearing, the men released a statement calling the outbreak a "terrible accident" and saying they were shocked and saddened by it. The statement said the charges do not imply they knew about the contamination or that they should have known about it.

The misdemeanor "was the best, most serious charge we could find," said Jeff Dorschner, the prosecutors' spokesman. Prosecutors decided to pursue the case because so many people were affected.

The Centers for Disease Control linked cantaloupe grown at Jensen Farms to the listeria outbreak that began at the end of August 2011. In October of that year, the Food and Drug Administration found that Jensen Farms' packing and storage facilities likely helped spread the listeria and directly contributed to the outbreak. Cases associated with the strain of listeria traced to Jensen Farms ended in December 2011.

Listeriosis from listeria bacteria is a serious infection that primarily affects older adults, pregnant women, newborns and adults with weakened immune systems. Fever and muscle aches sometimes accompanying diarrhea or other digestive problems. Pregnant women face a risk of miscarriage, which one survivor did experience. Convulsions also are possible in severe cases, according to the CDC.

The FDA said one piece of equipment, a used potato washing machine bought just before the outbreak, was its possible cause and cited dirty water on the floor of the packing center as well.

"Several areas on both the washing and drying equipment appeared to be un-cleanable, and dirt and product buildup was visible on some areas of the equipment," according to the FDA report.

The way the cantaloupes were cooled after being picked may have exacerbated the listeria growth, the FDA said. Another possible source of contamination was a truck that frequently hauled cantaloupe to a cattle operation and was parked near the packing house.

The outbreak was the deadliest outbreak of foodborne illness since 1924. The CDC said people living in 28 states consumed contaminated cantaloupe.

The outbreak was a setback for farms in southeast Colorado's Rocky Ford cantaloupe region, where hot, sunny days and cold nights produce fruit known for its distinct sweetness.

Jensen Farms was located about 90 miles east of Rocky Ford, but the Jensens used the Rocky Ford name and sales dropped across the region. Later, Rocky Ford farmers patented the Rocky Ford name, hired a full-time food safety manager and built a central packing operation where melons are washed and rinsed.

Tammie Palmer of Colorado Springs, Colo., whose husband, Charles, became ill after eating the cantaloupe and died in July 2013, said the criminal case won't help her.

"My husband is already dead," she said. As Charles Palmer was being treated for listeria, doctors discovered cancer and he never fully recuperated from his listeria infection.

She said a just outcome would be to prevent the Jensens from farming again or having any involvement with the food industry. Palmer and her husband filed a lawsuit seeking $2 million from Jensen Farms, but it hasn't been resolved. He had more than $250,000 in medical bills.

"I was hoping everything would be settled and I could do something with my husband," she said. "But that's not going to happen."